SKM 2023 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 59: Poster Session: Topology

TT 59.9: Poster

Donnerstag, 30. März 2023, 15:00–18:00, P2/OG4

Ultrasound propagation in candidate material for electron hydrodynamics, Weyl semimetal WTe₂ — •Rafal Wawrzynczak¹, Stanislaw Galeski^1,2, and Johannes Gooth^1,2 — ¹Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany — ²Physikalisches Institut, Universität Bonn, Nussallee 12, D-53115 Bonn, Germany

Interactions between electrons might lead to the appearance of a regime where the dominating time-scale is defined by momentum-conserving processes. This is manifested by electron liquid exhibiting features characteristic for classical liquids, like Poiseuille flow, resulting in non-Ohmic, sample-width-dependent resistivity. This was recently observed in a two-dimensional metal PdCoO₂ and two Weyl semimetals. Neither of the observations was accounted for with complete microscopic description. For WTe₂ there was proposed a mechanism based on the electron-electron scattering process involving a virtual phonon.

Here we report results of ultrasound propagation study performed on WTe₂ Weyl semimetal. We have analyzed temperature and field dependence of propagation of longitudinal and two transverse modes of different polarization propagating along the a crystallographic directions. The data shows anomalous decrease in speed of the longitudinal mode below 10 K and non-monotonous T-dependence of its attenuation. Moreover, quantum oscillations observed in all six measured quantities reveal the details of coupling between measured phonon modes and different parts of systems Fermi surface.